A diaphragm formed by a sheet forming method using a single material for the diaphragm and an edge, that is, a so-called a vibrator which includes a fixed edge has been proposed (Patent Literature 1).
The following drawback has been pointed out in Patent Literature 1. In a fixed edge B illustrated in FIG. 9 in Patent Literature 1, an edge portion 12a is thinner than a cone diaphragm portion 13a by a paper making method to improve a compliance of the edge portion 12a as compared to that of the cone diaphragm portion 13a. Thus, the edge portion 12a needs to be made thinner to further enhance the compliance of the cone diaphragm portion 13a, and the fixed edge has therefore drawbacks in that the enhancement of the compliance has made vibration proof weaker, and the fixed edge made of pulp has caused the compliance to be susceptible to outside air environment, particularly to a moisture.
That is, the technique disclosed in Patent Literature 1 has a problem in that the diaphragm and the edge made of a single common material has caused a failure to meet individual needs with respect to the diaphragm and the edge.